Pot



April 16, 1929.

F. K. LANDGRAF ET AL POT Filed March 27, 1928 INVENTORS contain chromium,

UNITED STATES PATENT OFFICE.

FREDERICK x. mnnem, o BUBGH, rnnnsnvaum, nunen, PENNSYLVANIA,

F GRAFTON, AND EDWARD S. FITZ SIMMONS, OF IPITTS-v ASSIGNORS TO FLANNEBY BOLT COMPANY, OF PITTS- A. CORPORATION OF DELAWARE. 4

mar.

Application filed March 2?, 1928. Serial No. 265,012.

Our invention relates to pots, and more particularly to pots for heat treating or carburizing metallic objects,

be understood that the other purposes.

The heat treating although it is to pots may be used for or carburizing of metallic objects is usually conducted at high temperatures in pots of a heat resisting alloy.

Alloys frequently used for such purposes iron and nickel. For objects a salt bath is heat treating various often used in the pot burizationprocesses 1t is and for certain cardesirable to fill the pot with a cyanide bath. When this is done it is frequently molten chemical baths found that the heated or in the pot, together with the air which comes in contact with the bath, have a corrosive of the pot.

' iron, ingot iron or Substantially pure iron,

steel action upon the wall such as wrought of extremely low carbon content is resistant to the action of alkalies. Consequently,

for contaimng cyanide alkaline nature.

iron has been used and other baths of an However, at the high temperatures at which such baths are maintained, an iron pot which comes in contact with the air gradually rusts away so thin as to render until the walls become the pot unserviceable.

The deterioration of such iron pots from outside oxidation is relatively rapid and they last only a comparatively short time.

It has heretofore been proposed to provide an inner section of the pot of substantially pure iron and heat resistant alloy.

fitted separately and an outer section of a The sections are made together. Diflicultyhas been experienced in shaping'and assembling the separated fections in the shape sections as small imperof either section are apt to prevent the sections from fitting snugly together when assembled.

We provide a pot and cover one or both of the surfaces of the pot with a protecting layer of metal deposited by a welding operat1on. By welding metal to the pot,

the layer of covering the covering layer conforms to the shape of the pot and does not require any previous efforts to irregularities being the pot. is welded to the inner insure against minor present in the shape of The covering and protecting layer surface or the outer a pot of very pure surface of the pot, as maybe desired, in accordance with the nature of the metal used in the pot.

Where the pot is of 'a heat resisting alloy the interior is covered with a protective layer that is resistant to the action of the bath which the finished pot is desi ed to contain. Where the potis made 0 a ma terial that is resistant to the action of the Figure 2 is a similar view showing a protective layer deposited on the inner surace of the pot,-and

Figure 3 is a similar view showing protective layers deposited on both the inner and outer surfaces of the pot. 7

Referring toFigure 1, a pot 2 resistant to the action of a bath 4 contained therein is provided with an outer protective layer 5 of material resistant to the action of the surrounding air and other gases at the temperature at which the pot is operated. Where the bath 4 is of an alkaline nature, such as cyanide, the pot 2 is of substantially pure iron, such as wrought oringot iron, or steel of extremely low carbon content. Alloys suitable for the protective layer 5 contain chromium, iron and nickel.

By applying the protective layer 5 to the pot 2 either by machine or by a hand weldmg process, the protective layer conforms to the shape of the pot 2 and eliminates the trouble and expense heretofore required for insuring that an inner or outer pre-shaped covering for a pot conform to and fit snugly with the adjacent surfaces of the pot. The dissimilar metals are united by a thin layer of an alloy of the metals, which makes a bond between the metals. The bond prevents the separation of the metals during tive layers 5, 7, 10 and 11 as being applied to their associated pots in circnmferentially extending series of united beads of metal deposited-by the welding operation, it is to be understood. that they may be applied in substantially longitudinally extending series of united beads.

While we have shown and described the invention in connection with the heattre'ating or carburization of metallic objects, it is to be understood that the invention is capable of application to other (processes by' suitably selecting the metals an alloys comprising the pot and protective layer or layers. It is to be understood that various I changes may be made in the invention with out departing from the scope of the ap-. pended claims.

We claim: 1. A ot having a bottom of substantially semi-sp eroidal contour comprising a portion resistant to the action of an alkaline bath, and a portion resistant to the action of heat at the operative temperature of the rality of united by-a welding operation.

bath, one of said portions comprising a plu- 2. A pot having a bottom of substantially semi-spheroidal contour com )rising an inner portion composed of a metallic material resistant to the action of a bath'and an outer portion resistant to the action of heat,.one of said portions consisting of united beads of welded material.

3. A pot for holding a bath to be heated comprising inner and outer layers of dissimilar metals-resistant to the action of an erosive bath and'to the action of heat, re:

spectively, one of said layers being formed in situ by united beads of metal deposited by a welding operation.

beads of material deposited 4a. A pot for holding a bath to be heated similar metals resistant to the action of an erosive bath and to the action of heat, re-

spectively, one of said layers being formed in situ by molten metal deposited by a welding operation.

' 5; A pot for holding a bath to be heated comprising inner and outer layers of .dis-

comprising inner and outer continuous impervious layers of dissimilar metals resist ant to the action of an erosive bath and to the'action of heat, respectively, one of said layers being formed in situ by united beads of metal deposited by a welding operation.

In testimony whereof we have hereunto set our hands.

FREDERICK K.-LANDGRAF. EDWARD S. FITZ SIMMONS. 

